Making casting molds



Patented Jan. 18,1927.

1,614,820 UNITED STATE PATENT OFFICE.

' ADOLI BECK, mm, Gm.

IAKIN'G CASTING HOLDS.

Io Drawing. Original application fled Kay 25. 1922. Serial 10. 583,711, and in Germany September 4, 1922. Divided and this application flied July 22, 1825. Serial, 10. 45,420.

My invention refers to the preparation of molds for the melting and casting of myself easily oxidizable metals such as magnesium and its alloys. It is an object of my invention to provide means whereby the oxidizing action of steam on castings of such metals is prevented, especially as regards castings made in sand molds.

As is well known to thme skilled in the art, ifit is intended to cast metals, such as magnesium and its allo s, which are liable to get oxidized in heate condition, the easting being effected with the aid of the sand molds hitherto generally employed, such molds must be carefull dried, in order to obtain good castings. f the molds are not dried carefully, a reaction will take place between .the metal and the water present in the mold and more especially in the sand,

and a similar reaction is then liable to takeplace between the metal and the molding ma terial, such 'as sand, such reaction rendering the casting at least inferior in outer appearance. If great quantities of water are still present in the mold, explosion-like pheu'omena are even likely to occur. In U. S. Patent No. 1463609 granted to Karl Gersbach OskarHermann Weber and a method of casting is described which allows avoiding the i ition of the metal, provided that the mol s are carefully dried, this method substantially consisting in dusting the mold with a material which will not react witlrthe molten metal, F either as such or in-the form of its products of oxidation.

I asume this protective effeet to be due to the action of the gases or vapors developed from the. protective material in contact with the hot metal and which prevent the access'of air or steam to the metal.

I have now ascertained that by'admixing 'certain materials to the sand or other material from which the mold is prepared for casting, I obtain the surprising result that the drying of the mold and ofthe sand or the like contained therein is no more necessary the presence of moisture being innoxious so that I-am now enabled to east the metals in question in undried molds made of green sand. These materials (which may be called protective substances) are those described in the specification above cited, as 'being adapted to prevent oxidation of the castings when intensely dried molding sand is used, and more especially sulphur. The peculiar action of the protective substances has not yet been cleared up completely. It seems that the steam and air are sufliciently diluted with gases or vapors produced from these substances or that they prevent in some other way the access of water vapor to the hot metal so that no visible action of the steam upon the metal occurs. .However, I

wish it to be understood that this is merely.

obtained even at those places where the easting is comparatively thick such as gates, inasmuch as the protective gases or vapors are not developedmerely on the surface of the mold, as in the ease of superficial powdering or spraying on, but also from deeper layers in correspondence with the gradual heating of the mold by the metal as it flows in. However, in certain cases I may admix the protective material with the sand and besides powder or spray it onto the mold.

A similar effect within the scope of my invention might be-obtained also by developing gases or vapors from the protective materials spoken of above out-side the mold and introducing them into the mold immediately before the casting. However, if this is done, the protective effect will be less powerful for the reason that the concentration of the protective masses or vapors will not be as great between the mold and the metal, as if they are generated in the mold too ture of undried molding material and sulphur, and forming such mixture into a mold.

2. The method of making molds for east- 5 ing easily oxidizable metals and alloys in undried molds, comprising preparing a mixture of undried molding material and 1% sulphur, and forming such mixture in 'to a mold.

3. The inethod ofmaking molds for easting easily oxidizable metals and alloys in undried molds, comprising preparing a mixture of undried molding material and more than 1%, but less than 35% sulphur, and forming such mixture into a mold.

In testimony whereof I affix my signature.

ADOLF BECK. 

